The Magnificent Seven’s remarkable performance defines the stock market in 2023. This basket of the seven largest companies in the S&P 500 index gained an average of 111% vs. an average gain of 9% for the other 493 companies. The combined impact of huge index weights and outsized performance made 2023 one of the most top-heavy markets in history. Whenever assets outperform to this degree over just a few quarters, the valuation alarm bells start clanging. Could the fundamentals possibly justify such a massive advance, or is AI mania responsible for the outperformance?